1. Field of the Invention
This invention concerns a paper colouring apparatus, particularly for rotation press machinery. The apparatus for the colouring ordinarily of white paper to a desired colour before the paper web is drawn into the printing press.
2. Prior Related Art
In such apparatuses the paper web passes a number of rollers. Some of the rollers must be displaceable, so that the paper web can pass through the apparatus without coming in contact with dye bearing rollers, in the event the paper is not to be coloured before entering the press. The displaceable rollers must also be adjustable such that they touch the neighbouring rollers with a predetermined pressure when the apparatus is set for colouring. It is important that this pressure be uniform along the entire length of the roller.
With the known apparatuses of this type, the rollers are displaced and adjusted with the aid of mechanical devices such as screws, eccentrics and springs.
A drawback with such an apparatus is that it is very difficult and time-consuming to adjust the rollers; this causes increased paper wastage and, in part, lower quality colouring.
It is also a disadvantage of a known apparatuses of this type that they are only arranged to colour one side of the paper web. If, as an alternative, the other side of the paper web is to be coloured, a similar apparatus must be installed with a different roller adjustment in series with the first.
A further disadvantage of the known apparatuses is that the roller, due to incorrect adjustment, may easily cause the apparatus to exert greater resistance to the feed through of the paper web, so that the paper web length control of the press is disturbed. This disadvantage is particularly pronounced when printing data forms and which comprise a set of several copies.